Method of oil coagulation utilizing entrained gas

Abstract

The present invention proposes the utilization of a bed of finely divided, naturally occurring, strongly hydrophilic, strongly oleophobic materials for the coalescent removal of oil from water-oil mixtures containing appreciable amounts of entrained gas, such as crude oil. Preferably, the bed materials have a water wetting-to-oil wetting ratio greater than about three and are of a particle size ranging from about 20 mesh to about 60 mesh. Specifically utilized materials include fruit pit shells and nut shells such as apricot pit shells, peach pit shells, walnut shells and the like. The method consists of flowing a water-oil mixture containing entrained gas through a deep bed of fine particles and coalescing the oil internally of the bed into globules of a size incapable of passing through the interstices of the bed. The oil-free water effluent is recovered from the bed during coalescing of the oil and the oil is periodically recovered and removed from the bed by decanting or backwashing, the oil globules being readily released from the strongly oleophobic particles of the bed for flotation from the bed. Oil removal efficiencies in excess of 90% during a single passage through the bed are readily attained with the aid of the entrained gases, which materially increase the efficiency of oil-water separation, particularly in light oils or crude oil.

What is claimed is: 
     
       1. In a method of separating an oil-water mixture, the steps of entraining a gas into the oil-water mixture, flowing the mixture with the entrained gas through a bed of individual, naturally occurring media particles of fruit pit shells or nut shells of a size ranging from about 20 mesh to about 60 mesh and having a water wetting-to-oil wetting ratio of at least about three, agglomerating and entrapping the oil in interstices of the bed, and recovering from the bed water which is substantially free of oil.